The present invention relates to high speed dot matrix impact printers and more specifically to the structure of an arm which carries at one end a stylus at substantially right angles to the arm which stylus impacts a record material through an inked ribbon to apply a dot to the material.
In said U.S. Pat. No. 4,136,978, there is disclosed a dot matrix printer operating at speeds of 600 characters per second and higher. Each character is formed in accordance with a prescribed matrix such as 5.times.7, such a matrix requiring 7 stylii disposed in a vertical column. Each stylus is provided with an individual driver mechanism comprising a magnetic circuit for holding an arm in a cocked position against a spring force and releasing the arm upon command to permit the spring to move the arm rapidly in a printing direction. The arm carries a printing stylus at one end; the stylus being generally perpendicular to the arm. Impact of the stylus against the recording material and underlying platten causes a rebound which aids the recapture of the arm by the magnetic circuit.
It is believed apparent that the arm and the stylus must be of quite light weight and thus of thin material to permit the high speeds of operation achieved by the aforesaid device. The strain on the bond between the stylus and the arm is severe considering the thinness of the material and the limited bonding area of the construction of the arm in the aforesaid device.
It is an object of the present invention to provide an arm for dot matrix impact printers which permits a printer stylus to be securely held at the end of the arm and which provides thickened top and bottom portions of said arm for optimum strength-to-weight ratio.
It is another object of the present invention to provide an arm for dot matrix impact printers constructed from a single stamping or other appropriately formed blank which when folded provides two C-shaped members joined by a web adapted to encircle substantially half a stylus whereby to provide a large surface of contact therebetween and permit a secure bonding by brazing or otherwise.